class_docstr: An abstract base class for generating synthetic time series data.
  Generates a 1-dimensional grid x(0), x(1), ..., x(n-1), where x(i) = x0 + i * step.
  Then generates a time series y(0), y(1), ..., y(n-1), where y(i) = f(x(i)) + noise.
code: def x0(self):
      return self._x0
  
imports: import numpy
  import pandas
  from operator import add
  from functools import reduce
  from typing import Callable, List, Union
  from merlion.utils.time_series import UnivariateTimeSeries, TimeSeries
label_desc: Use image node_id 4 for calling the TimeSeriesGenerator obj's underlying member method code with example usage: obj.x0() and returns: self